1. Technical Field
The present invention relates to a method of disposing phosphor layers and, more particularly, to a method of disposing phosphor layers, which can prevent damage to phosphor and also effectively dispose phosphor layers at desired locations of Light-Emitting Diodes (LEDs) when the phosphor layers are detached and disposed at the top surfaces of the LEDs.
2. Description of the Related Art
Recently, an LED in which aluminum (Al) or lanthanide (In) has been added to gallium nitride (GaN) has been in the spotlight due to a long lifespan, low power consumption, excellent brightness, and eco-friendly factors that are not harmful to the human body as compared with conventional incandescent bulbs. In particular, an LED chip that provides white light using phosphor layers has been further in the spotlight.
Such an LED is being used in automotive lightings, traffic lights, and the Back Light Unit (BLU) of a liquid crystal display due to the above advantages.
Recently, MacAdam's Ellipse Rule was proposed as an index for evaluating whether color coordinates measured in an artificial light source are identical with color coordinates when being seen by the human eye. MacAdam's Ellipse Rule provides a four-step criteria. In the United States, an artificial light source that does not comply with three steps of MacAdam's Ellipse rule is not allowed to be sold. In order to satisfy the three steps of MacAdam's Ellipse rule, it is very important to reduce a color deviation of white light. Korean Patent Laid-Open Publication No. 10-2008-0070193 discloses a phosphor film in which a phosphor is formed on a surface of a film made of resin. In order to dispose the phosphor film at the top surface of an LED, a process of detaching or taking the phosphor film is necessary. If the phosphor film is detached or taken, it is very difficult to reduce a color deviation of white light because the phosphor is damaged or is not effectively disposed at the top surface of the LED due to electrostatic force or adhesive force between the phosphor and the film made of resin.